UNIVERSITY  OF  CALIFORNIA. 


AGRICULTURAL   EXPERIMENT   STATION. 
BERKELEY,   CAL. 

E.  W.  HILGARD,  Director.  BULLETIN    No.   114. 


The  Causes  of  "Frogging"  and  "Bloating"  of  Prunes. 


DECEMBER,   1896. 


Fig.  1. 

Three  large  prunes  showing  proper  checking  of  the  skin  after  dipping. 
Three  small  prunes  subjected  to  the  same  treatment,  but  unchecked. 


Fig.  2. 

Section  through  the  slit  of  a  properly  checked  prune  (enlarged  about  20u  diameters). 
A.  A.— Ends  of  the  ruptured  epidermis.    B  —  Unbroken  cells  of  the  Hesh. 


THE  CAUSES  OF  "FROGGING"  AND  "BLOATING"  OF  FRUNES. 

By  P.  T.  Bioletti. 


During  the  season  of  1895  numerous  demands  were  made  on  the 
Agricultural  Experiment  Station  for  information  concerning  the  so- 
called  "frogging"  and  "bloating"  of  prunes.  There  was  evidently 
wide  diversity  of  opinion  as  to  the  cause,  nature,  and  best  methods  of 
avoiding  these  troubles.  Under  the  direction,  therefore,  of  Prof.  E.  W. 
Hilgard,  I  visited  several  drying  establishments  in  the  Santa  Clara 
Valley,  in  order  to  examine  into  the  trouble  on  the  spot. 

As  the  claim  was  made  that  "frogging"  and  "bloating"  were  directly 
attributable  to  the  practice  of  lye-dipping,  or  at  least  that  the  pricking 
process  prevented  these  evils,  both  processes  were  investigated.  As 
representative  of  the  lye-dipping  process,  the  West  Side  Drying  Estab- 
lishment was  visited  at  the  instance  of  Mr.  S.  P.  Sanders.  From  direct 
personal  observation  and  from  the  reports  of  those  engaged  in  drying 
the  prunes,  the  following  facts  were  obtained: 

The  prunes,  before  drying,  pass  through  a  nearly  boiling  solution  of 
lye,  and  then  through  water.  A  sample  of  the  lye  solution  taken  from 
the  trough  as  the  prunes  were  passing  through,  showed  1.6%  of  alkali. 
Most  of  the  prunes  as  they  come  from  the  lye  are  covered  with  minute 
cracks  or  "checks."  Some  are  acted  upon  too  energetically,  and  come 
out  quite  denuded  of  their  skin.  For  others  the  treatment  is  appar- 
ently too  mild  and  fails  to  break  the  skin  at  all. 

It  is  prunes  of  this  last  class,  coming  from  the  process  looking  smooth 
and  unchanged,  that  result  in  frogs.  The  properly  "checked"  prunes 
begin  to  dry  immediately,  the  skin  wrinkling  in  minute  folds.  The 
flesh  remains  of  a  light,  bright  amber  color,  and  the  outside  of  a  clear 
purplish-brown,  differing  from  the  shiny  black  of  the  pricked  fruit. 
The  over-treated  prunes  simply  dry  up  too  quickly  and  become  hard 
and  too  dry.  The  prunes  with  smooth,  "unchecked  "  skin  do  not  show 
signs  of  drying  immediately,  but  remain  smooth  and  round  for  several 
days,  till  they  become  a  dirty  brown  and  the  flesh  becomes  discolored. 

When  the  good  prunes  are  dry  the  frogs  are  picked  out  by  hand, 
put  on  separate  trays,  and  dried  for  several  days  longer.  When  dry  the 
frogs  are  smaller  than  most  of  the  good  prunes,  of  a  duller  color,  and 
have  a  less  finely  wrinkled  skin.  The  appearance  of  the  skin  is  similar 
to  that  of  the  pricked  prunes  with  regard  to  smoothness,  but  they  have 
not  the  bright  black  color  of  the  latter.  When  the  frogs  are  dry  they 
are  thrown  in  with  the  rest  of  the  prunes;  but  being  mostly  small,  they 
are  separated  by  the  grader  and  fall  into  the  lowest  grade.  The  usual 
proportion  of  frogs  is  said  not  to  exceed,  on  the  average,  one  per  cent. 
One  year,  certain  orchards  will  produce  the  largest  proportion  of  frogs, 
another  year  others  will  do  so.  In  general,  it  is  the  orchards  producing 
the  largest  crops  that  produce  the  largest  percentage  of  frogs.     In  the 


—  4  — 

best  drying  weather  there  are  few  or  no  frogs  produced,  while  in  damp 
or  cloudy  weather  the  proportion  is  relatively  high.  If  a  tray  is  shaded 
for  any  length  of  time  it  will  contain  a  larger  number  of  frogs.  Fewer 
frogs  come  from  those  orchards  where  only  the  prunes  which  fail  naturally 
from  the  trees  are  picked  up  than  from  those  where  the  practice  is  to  shake 
the  trees.  The  first  picking  and  the  last  contain  the  greatest  quantity 
of  frogs. 

A  neighboring  drying-yard  was  examined  where  the  fruit  was  graded 
before  dipping.  The  result  was  that  among  the  first  and  second  grades 
there  were  scarcely  any  frogs;  but  in  the  third  or  smallest  grade  there 
were  a  good  many. 

Orchards  which  produced  practically  no  frogs  this  year  were  visited. 
The  trees  were  found  bearing  a  rather  small  crop  of  very  fine,  large,  and 
well-ripened  prunes.  The  trees  were  pruned  in  such  a  way  that  no  part 
of  the  tree  was  very  close-topped,  and  no  part  unduly  exposed  to  the 
sun;  the  trees  being  kept  fairly  open,  so  as  to  allow  of  bearing  wood 
even  in  the  center.  They  were  pruned  back  enough  to  avoid  all  danger 
from  breaking  branches,  but  not  enough  to  make  the  trees  too  dense. 

Other  orchards  which  were  producing  many  frogs  this  year  were  next 
examined.  The  trees  were  bearing  very  large  crops,  and  many  of  them 
had  large  branches  broken  off  by  the  weight  of  the  fruit.  The  fruit  on 
these  broken  branches  was  small  and  hard,  and  was  not  so  sweet  or  so 
well  flavored  as  that  on  the  rest  of  the  tree. 

A  drying  establishment  where  a  pricking  machine  was  used  exclu- 
sively was  also  visited.  The  prunes  while  passing  over  the  needles 
were  sprayed  with  warm  water,  but  no  lye  was  used.  In  passing  over 
the  needles  the  prunes  were  pricked  on  about  half  their  surface;  that 
is,  on  a  central  zone,  the  ends  being  almost  intact.  The  holes  were 
from  one  sixteenth  to  one  quarter  of  an  inch  apart,  and  each  prune  had, 
besides  these  holes,  from  two  to  about  ten  little  slits  made  by  the 
needles,  to  which  the  proprietor  looked  principally  for  the  useful  effects 
of  the  process.  A  certain  amount  of  juice  was  lost  through  these  slits, 
but  perhaps  not  more  than  is  lost  from  the  over-treated  fruit  in  the  lye 
process.  The  prunes  were  black  and  shiny  on  the  outside,  of  very  good 
appearance,  but  inside,  the  flesh  was  darker-colored  than  that  of  the 
lye-dipped  prunes.  There  were  practically  no  frogs  that  could  be  picked 
out. 

OBSERVATIONS  IN  THE  LABORATORY. 

On  September  12,  1895,  samples  of  fresh  'prunes  were  received  for 
experiment  from  Mr.  S.  P.  Sanders,  as  follows: 

1.  Prunes  that  were  gathered  from  branches  broken  down  by  the 
weight  of  fruit.  The  fruit  was  still  attached  to  the  branch,  though  the 
prunes  from  the  unbroken  branches  of  the  same  tree  had  nearly  all 
fallen  and  been  gathered. 

2.  Prunes  from  the  unbroken  branches  of  the  same  heavily  laden 
trees  as  No.  1.     The  fruit  was  small,  but  in  good  condition. 

3.  Prunes  from  trees  bearing  a  moderate  crop  of  fine,  well-ripened 
fruit.     All  were  soft  and  a  few  showed  signs  of  commencing  to  dry. 

The  prunes  (No.  1)  from  broken  branches  were  treated  with  a  boiling 
1.6%  lye  solution.  After  20  seconds  immersion  only  one  prune  was 
checked.  After  40  seconds  some  skins  were  split  in  consequence  of 
partial  cooking,  but  there  were  no  genuine  checks.    After  60  seconds  the 


—  5  — 

prunes  had  suffered  from  cooking,  but  were  not  checked.  A  3%  boiling 
lye  solution  was  then  tried.  Different  samples  of  the  prunes  were 
dipped  for  5,  10,  20,  and  for  60  seconds,  with  practically  the  same  results 
as  with  the  weaker  solution. 

Of  the  prunes  (No.  2)  from  the  unbroken  branches  of  heavily  laden 
trees,  about  half  felt  soft  and  half  hard.  The  hard  and  the  soft  fruit 
were  treated  separately,  but  with  practically  the  same  results;  about  the 
same  proportion  of  each  failing  to  check  properly.  Immersion  for  20 
seconds  in  a  boiling  6%  lye  solution  checked  about  half  of  the  prunes 
well.  Most  of  the  rest  were  checked  more  or  less  insufficiently,  while  a 
few  were  not  checked  at  all.  These  last  presented  the  same  characteris- 
tics as  the  fruit  from  the  broken  branches,  and  like  them  the  skin  could 
not  be  broken  short  of  cooking. 

The  first-class  prunes  (No.  3)  were  tried  first  with  a  1.6%  solution.  In 
(  this  strength  of  solution  at  the  boiling  temperature  from  20  to  30  seconds 
was  the  best  time  of  treatment.  More  than  40  seconds'  immersion  com- 
pletely removed  the  skin  in  places.  With  this  strength  of  lye  (1.6%), 
boiling  temperature,  and  20  seconds'  immersion,  all  the  prunes  of  this 
lot  checked  perfectly.  A  3%  solution  was  found  too  strong,  even  with 
only  10  seconds'  immersion.  A  shorter  time  failed  to  check  the  skin,  and 
a  longer  completely  removed  it.  Experiments  at  different  temperatures 
showed  that  if  the  lye  is  much  below  the  boiling-point,  the  skin  does  not 
check.  If  left  in  the  lye  longer  at  these  lower  temperatures  the  skin 
finally  cracks  like  that  of  the  small  prunes  described  above,  and  instead 
of  innumerable  shallow  cracks  there  are  a  few  deep  splits. 

All  the  prunes  of  this  series  of  experiments  were  placed  on  trays  and 
put  to  dry  in  the  sun  in  as  nearly  similar  conditions  as  possible  to  those 
which  obtain  in  the  drying-yards.  The  results  were  exactly  the  same 
as  those  noted  at  the  West  Side  drying-yard.  The  prunes  which  had 
failed  to  check  turned  brown  and  were  long  in  drying;  the  others  dried 
in  a  few  days.  An  attempt  was  made  to  determine  the  presence  of  a 
mold  or  other  micro-organism  within  the  tissue  of  the  brown  prunes, 
but  without  success.  A  determination  of  the  sugar  contents  in  the  two 
kinds  of  prunes  was  made  by  Mr.  Colby,  with  identical  results  for  each 
kind.  Microtomic  cross-sections  of  the  skin  were  made  in  order  to 
determine  if  the  relative  thickness  of  the  epidermis  was  in  any  way 
connected  with  the  failure  to  check.  A  slight  difference  of  thickness 
was  found,  but  not  enough  to  account  for  the  great  difference  of  behavior 
in  dipping.  Ten  measurements  of  the  thickness  of  the  skin  of  prunes 
(No.  1)  from  broken  branches  showed  an  average  of  24.9  fi  (microns), 
while  the  average  of  eight  measurements  of  the  skin  of  large,  well- 
ripened  prunes  (No.  3)  was  23.6  p-.  Under  the  microscope  the  walls  of 
the  epidermal  cells  of  the  small  prunes  appeared  thicker  and  retained 
their  shape  better  under  the  operations  of  hardening,  imbedding,  and 
cutting,  showing  that  they  were  of  a  more  resistant  nature. 

The  following  three  samples  of  dried  prunes  were  received  later  in  the 
season  from  Mr.  S.  P.  Sanders: 

4.  Frogs.  These  were  small,  hard,  smooth-skinned  prunes  of  the  typi- 
cal dirty-brown  color  outside,  and  dark  color  inside.  They  averaged  120 
to  the  pound,  and  showed  35.25%  of  sugar.  The  skin  showed  no  checks. 
The  higher  sugar  content  as  compared  to  No.  5  is  to  be  accounted  for  by 
over-drying. 


—  6  — 

5.  Large  prunes  of  good  quality.  Light  purplish  color  outside,  with 
finely  wrinkled  skin,  and  bright  amber  color  inside.  These  averaged 
43.2  to  the  pound,  and  showed  33.25%  of  sugar.  The  skin  showed  the 
customary  close  checking  of  successfully  dipped  prunes. 

6.  Bloaters.  These  prunes  were  very  large,  a  little  darker  in  color 
than  No.  5,  and  with  equally  fine-wrinkled  skin.  The  inside  was  dark- 
colored  in  places,  but  in  general  resembled  that  of  the  prunes  of  No.  5 
in  texture,  though  a  little  harder  and  more  thoroughly  dried.  They 
were  hollow,  and  in  many  cases  the  stone  was  split.  They  averaged 
37.4  to  the  pound,  and  showed  39%  of  sugar.  The  skin  was  finely 
checked,  at  least  as  thoroughly  as  in  No.  5. 

• 

"frogs"  and  "bloaters." 

At  the  drying-yards  which  I  visited,  the  terms  "frogs,"  " frogbellies," 
and  "  bloaters "  seemed  to  be  used  indiscriminately.  There  are,  how- 
ever two  things,  very  distinct  both  as  to  cause  and  effect,  confused 
under  these  names.  The  prunes  which  I  will  call  bloaters,  for  the  sake 
of  distinction,  are  generally,  perhaps  always,  large  prunes,  originally. 
In  drying  they  swell  up  to  half  again  their  natural  size,  on  account  of  a 
gas-producing  fermentation  around  the  pit.  They  become  hollow  and 
the  pit  frequently  splits  in  two.  In  grading,  they  all  fall  in  with  the 
largest  size,  and  in  the  after-dipping,  owing  to  the  air  space  within,  they 
float  and  can  be  separated.  In  quality,  as  far  as  eating  is  concerned, 
they  are  almost  equal  to  the  first-class  prunes,  but  are  not  so  attractive  in 
appearance,  on  account  of  their  swollen  look.  The  fermentation  that  they 
undergo  is  slight  (in  the  cases  that  have  come  under  my  observation), 
as  is  proved  by  the  high  percentage  of  sugar  which  they  contain.  This 
is  higher  than  in  the  case  of  the  good  prunes;  a  fact  which  is  to  be 
accounted  for,  partly  by  their  more  complete  ripeness  when  gathered, 
and  partly  by  the  greater  amount  of  drying  which  they  undergo  on 
account  of  the  hollow  space  around  the  pit.  The  bloaters  are  doubtless 
large,  soft,  very  ripe  prunes,  which  in  falling  from  the  tree  become 
injured  in  such  a  way  as  to  allow  the  yeast  germs  which  exist  on  the 
skins  of  all  fruits  to  find  entrance,  probably  at  the  hole  left  by  the 
detachment  from  the  stem.  The  remedy  would  be,  frequent  gathering, 
in  order  not  to  allow  the  yeast  to  develop  in  the  shade  of  the  trees 
before  the  fruit  is  dipped  and  placed  upon  the  drying  trays.  The 
prunes  which  have  a  tendency  to  become  bloaters,  being  thoroughly 
ripened,  dry  quickly;  and  unless  the  fermentation  has  obtained  a  good 
start  before  they  are  placed  upon  the  drying-trays  it  will  have  no 
chance  to  develop  enough  gas  during  the  process  of  drying  to  puff  them, 
unless  the  drying  for  some  reason  is  slower  than  usual.  Pricking,  if  it 
were  deep  and  thorough  enough,  might  allow  the  gas  to  escape  as  given 
off  and  thus  prevent  bloating. 

The  prunes  which  I  will  call  "frogs,"  as  distinguished  from  "bloat- 
ers," are  of  an  altogether  different  character.  They  are  almost  always 
small  prunes  and  imperfectly  developed.  This  failure  to  develop  prop- 
erly may  arise  from  various  causes.  It  may  sometimes  be  due  to 
unsuitable  or  poor  soil,  but  in  the  cases  which  have  come  under  my 
observation  it  is  usually  due  to  overbearing.  A  tree  producing  too 
heavy  a  crop  fails  to  properly  mature  its  fruit;  it  cannot  supply  the 
requisite  nourishment  and  moisture  for  so  large  a  quantity.     The  fruit 


—  7    — 

upon  the  broken  branches  is  still  more  insufficiently  supplied  with  the 
necessary  material  to  complete  its  development,  and  it  is  precisely  this 
fruit  which  is  most  prolific  in  frogs.  Fruit  which  is  shaken  from  the 
trees  is  often  incompletely  developed,  and  therefore  results  in  many 
frogs.  Trees  were  observed  this  year  which  were  prematurely  deprived 
of  their  leaves  by  a  fungus  (Puccinia  pruni-spinosse,  Pers.).  The  fruit 
on  these  trees  was  precisely  of  the  character  of  those  which  become 
frogs.  In  short,  anything  which  prevents  the  fruit  from  attaining  a 
normal  and  complete  development  and  maturity  will  occasion  frog- 
ging.  The  way  to  prevent  their  production,  therefore,  is  to  keep  the 
trees  in  perfect  order,  and  allow  them  to  produce  only  a  reasonable  crop; 
to  gather  the  fruit  only  when  it  has  attained  the  proper  stage  of  matu- 
rity; and  to  dry  as  quickly  as  possible.  Prevention  is  better  than  cure; 
but,  if  prunes  are  to  be  dried  which  have  a  tendency  to  frog,  I  would 
strongly  advise  preliminary  grading.  This  is'  more  especially  important 
where  the  dipping  process  is  in  use.  The  smallest  grade  will  then  con- 
tain by  far  the  largest  part  of  the  prunes  liable  to  frog,  and  can  be 
treated  in  a  different  manner  from  the  good  prunes.  The  extra  expense 
would  be  more  than  counterbalanced  by  the  less  amount  of  sorting-over 
that  would  have  to  be  done  during  the  process  of  drying.  As  lye- dip- 
ping has  no  effect  on  the  frog  prunes,  they  should  be  pricked,  and 
unless  the  weather  is  of  the  best  drying  character  they  should  be  dried 
by  artificial  heat. 

In  view  of  the  great  influence  which  a  proper  system  of  pruning  may 
have  in  preventing  the  production  of  frogs,  a  series  of  photographs  of 
prune  trees  taken  by  Mr.  Sanders  is  of  great  interest.  These  photo- 
graphs have  been  kindly  donated  by  Mr.  Sanders  to  the  Station,  and  the 
most  instructive  of  them  will  be  reproduced  in  the  forthcoming 
agricultural  report. 

Judicious  pruning  prevents  the  production  of  frogs  by  regulating 
the  bearing  of  the  trees,  not  allowing  them  to  overbear  one  year  at  the 
expense  of  the  next,  nor  allowing  some  branches  to  carry  more  than 
their  share  of  the  load,  and  by  so  regulating  and  adjusting  the  branches 
that  they  will  have  the  maximum  bearing  strength;  that  is,  that  they 
will  bear  as  heavy  a  load  as  possible  without  breaking.  The  system 
advocated  by  Mr.  Sanders  and  exemplified  in  his  photographs  interferes 
as  little  as  possible  with  the  natural  form  of  the  tree.  It  simply  thins 
out  and  directs  the  growth  where  necessary.  It  aims  to  produce  a  tree 
with  an  upright  central  trunk,  from  which  the  branches  grow  out  alters 
nately  instead  of  opposite  to  each  other  in  pairs.  It  avoids  the  produc- 
tion of  weak  crotches,  and  especially  of  the  forks  which  are  caused  by 
the  repeated  cutting-back  system.  These  objects  are  attained  by  taking 
the  unpruned  tree  as  a  model  and  only  cutting  where  it  is  necessary  to 
prevent  irregularity  of  growth  or  of  shade,  and  to  distribute  the  bearing 
wood  as  evenly  as  possible.  A  tree  is  thus  produced  with  the  maximum 
breaking  strength  and  one  which  distributes  its  energy  properly  between 
the  production  of  foliage  and  fruit  and  the  storage  of  reserve  material. 
Trees  treated  in  this  way  do  not  have  to  be  held  together  with  iron  bolts 
and  bands  or  propped  up  with  wooden  crutches.  They  do  not  exhaust 
the  reserve  materials  stored  up  in  their  trunks  and  roots  in  the  produc- 
tion of  an  immense  crop  of  inferior  fruit,  nor  expend  their  energies  on 
an  unnecessarily  large  growth  of  new  wood  and  foliage. 


—  8    — 


LYE-DIPPING   AND    PRICKING. 


The  difference  of  opinion  regarding  the  relative  value  of  these  two 
processes  is  so  marked,  practical  men  who  have  investigated  and  even 
tried  both  methods  are  so  diametrically  opposed  in  their  views  on  the 
subject,  that  a  priori  there  would  seem  to  be  but  one  explanation,  viz., 
that  it  is  largely  a  matter  of  taste.  As  a  matter  of  fact,  each  process 
has  produced  dried  prunes  of  excellent  quality,  which  proves  that  if  the 
conditions  are  right  either  process  will  produce  good  results. 

The  accompanying  cut  (Fig.  2)  may  be  of  some  use  in  explaining  the 
differences  of  effect  between  the  checks  of  lye-dipping  and  the  holes  and 
slits  made  by  the  needle  machines.  It  represents  the  microscopic 
appearance  of  a  cross-section  through  a  check  of  the  proper  size.  It  will 
be  noticed  that  the  skin  is  simply  broken  and  very  little  of  the  flesh  of 
the  fruit  exposed.  A  few  of  the  thin-walled  cells  of  the  flesh  (B)  have 
collapsed,  owing  to  the  action  of  the  hot  lye,  but  none  of  them  are 
broken.  The  lye  check  is  thus  very  different  from  the  needle  slit,  which 
cuts  through  several  layers  of  the  soft  inner  cells.  This  deeper  cutting 
of  the  flesh  would  seem  at  first  glance  to  favor  rapid  drying.  That  it 
does  not  do  so  is  due,  in  the  first  place,  to  the  small  number  of  slits 
made  by  even  the  most  efficient  machine  compared  to  the  number  of 
checks  on  a  successfully  dipped  prune,  and  in  the  second  place  to  the 
fact  that  the  juice  which  is  allowed  to  flow  out  of  the  cells  broken  by 
the  needles  solidifies  and  chokes  up  the  slit.  When  a  prune  is  over- 
treated  by  the  lye  process,  the  skin  (A)  rolls  back,  exposing  more  of  the 
flesh  and  in  extreme  cases  completely  denuding  it. 

The  advocates  of  lye-dipping  claim: 

1.  That  the  prunes  are  more  thoroughly  cleansed; 

2.  That  they  dry  more  quickly; 

3.  That  the  skin  is  rendered  less  tough; 

4.  That  the  finished  product  is  of  better  appearance; 

5.  That  the  flavor  is  better. 

On  the  other  hand,  the  advocates  of  pricking  claim: 

1.  That  the  hot  water  they  use  cleans  the  fruit  perfectly; 

2.  That  the  prunes  dry  more  evenly; 

3.  That  no  frogs  are  produced; 

4.  That  the  finished  product  is  of  better  appearance; 

5.  That  the  flavor  is  better. 

With  certain  reservations  and  explanations  it  may  be  said  that  all 
the  claims  of  each  side  are  true.  With  some  pricking  machines  the 
washing  is  not  very  thorough,  but  with  the  best  arrangements  the 
cleaning  is  quite  satisfactory.  The  lye-dipped  prunes  dry,  according  to 
the  weather,  in  from  two  to  seven  days  less  time  than  the  pricked  prunes. 
But  the  greater  uniformity  in  the  drying  of  the  pricked  fruit  probably 
quite  offsets  this,  especially  where  there  are  many  tough-skinned  prunes 
which  the  lye  does  not  affect. 

The  third  claim  of  the  advocates  of  lye-dipping,  that  the  skin  is 
rendered  less  tough,  hardly  cuts  any  figure,  as  the  lye  acts  only  on 
those  prunes  which  have  naturally  a  tender  skin,  and  leaves  the  tough- 
skinned  ones  untouched.  It  is  with  regard  to  the  fourth  claim,  that  is, 
with  regard  to  the  appearance  of  the  fruit,  that  there  is  most  to  be  said 
on  both  sides.     All  that  the  unbiased  observer  can  remark  is  that  the 


—    9    — 

finely  wrinkled  skin  and  light  amber  color  of  the  lye-dipped  prunes 
are  very  attractive  to  those  whom  they  attract,  while  the  same  remark 
applies  to  the  smooth,  shiny  skin  and  black  color  of  the  pricked  prunes. 
As  it  is  a  matter  of  the  consumer's  taste,  the  market  should  quickly 
settle  this  question.  It  may  be  added  that  the  smooth  skin  and  black 
color  are  characteristic  of  the  best  French  dessert  prunes,  dried  without 
either  lye-dippihg  or  pricking;  and  as  habit  is  so  powerful  in  matters  of 
taste,  this  fact  will  certainly  have  influence.  With  regard  to  flavor  my 
own  impression  is  that  the  difference  is  so  slight  as  to  be  scarcely 
noticeable,  and  to  be  quite  obscured  by  the  least  diversity  in  the 
original  quality  of  the  fruit. 

The  conclusion,  therefore,  would  seem  to  be  that  if  we  are  dealing 
with  good  raw  material,  that  is,  fine,  well-ripened  prunes  and  good 
drying  weather,  the  choice  of  method  must  depend  on  which  appearance 
is  most  attractive  to  the  average  consumer. 

There  are,  however,  other  cases  to  be  considered.  In  the  case  of 
unevenly  developed,  mixed  lots  of  fruit  the  pricking  process  affords 
more  security  against  the  frogging  of  a  portion  of  the  fruit,  and  the 
product  is  much  more  uniform  in  appearance  and  in  time  of  drying. 
Uniformity  in  time  of  drying  is  very  important,  as  the  difficult  and 
expensive  hand-sorting  on  the  drying-trays  is  thus  reduced  to  a  mini- 
mum. The  mere  pricking  of  a  needle-hole  evidently  facilitates  drying 
but  very  little;  the  exuding  juice  almost  immediately  closes  up  these 
fine  holes.  It  is  otherwise  with  the  slits,  which,  being  similar  to  the 
effect  produced  by  the  lye  process,  facilitate  drying  much  more.  Still 
the  flow  of  sap  consequent  on  the  penetration  of  the  needles  into  the 
flesh  tends  to  close  up  the  finer  slits  also  and  thus  retards  drying,  while, 
however,  imparting  to  the  surface  that  shining  appearance  which  the 
lye-dipped  prunes  only  obtain  by  an  after-treatment. 

It  thus  appears  as  though  both  processes  had  their  place  in  the  prune- 
drying  industry,  each  serving  best  under  special  conditions;  and  that 
the  smaller  sizes  especially  would,  on  the  whole,  be  more  advan- 
tageously treated  by  the  pricking  than  the  lye-dipping  process. 


